Arrangement provided with at least two combustion flash bulbs

ABSTRACT

The invention relates to an arrangement for the successive ignition of at least two combustion flash bulbs in which each bulb is arranged in series with a thyristor. The invention provides a solution for rendering the thyristors conducting with the aid of a shift register which is provided with cores of a magnetic material having a substantially rectangular hysteresis loop.

United States Patent [191 Havas July 9, 1974 ARRANGEMENT PROVIDED WITHAT LEAST TWO COMBUSTION FLASH BULBS [75] Inventor: Pal Geza Havas,Emmasingel,

Eindhoven, Netherlands [73] Assignee: U.S. Philips Corporation, New

York, N .Y.

[22] Filed: June 4, 1973 [2]] Appl. No.: 366,445

[30] Foreign Application Priority Data 11/1971 Ellin 431/95 3,676,0457/1972 Watrous et a1. 431/95 Primary Examiner-Carroll B. Dority, Jr.Attorney, Agent, or Firm-Frank R. Trifari; Bernard Franzblau ABSTRACTThe invention relates to an arrangement for the successive ignition ofat least two combustion flash bulbs in which each bulb is arranged inseries with a thyristor. The invention provides a solution for renderingthe thyristors conducting with the aid of a shift register which isprovided with cores of a magnetic material having a substantiallyrectangular hysteresis loop.

8 Claims, 2 Drawing Figures PAI I JUL 91914 3823344 sum 2 or 2 Theinvention relates to an arrangementprovided with at least two combustionflash bulbs and with controlled semiconductor rectifiers forsuccessively igniting said bulbs, each bulb being arranged in serieswith such a controlled semiconductor rectifier, while each of theseseries arrangements forms part of a branch connecting two terminals of afirst direct voltage source, each of the controlled semiconductorrectifiers being provided with a control circuit.

A known arrangement of the type mentioned is described, for example, inUnited Kingdom Pat. specification No. 1,262,623. A drawback of thisknown arrangement is thatfor flashing a subsequent bulb in the row anumber of transistors is required to render the controlled semiconductorrectifier arranged in series with said subsequent bulb conducting.Furthermore, the closer a bulb is located near the end of the row ofbulbs, the greater the number of required transistors. In addition, ifonly one of these transistors does not operate properly, aninterconnection to a subsequent bulb is not established Anobject of theinvention is to provide a simple arrangement in which the number ofelements for interconnection to a subsequent bulb is small.

According to the invention an arrangement provided with at least twocombustion flash bulbs and with controlled semiconductor rectifiers forsuccessively igniting said bulbs, each bulb being arranged in serieswith such a controlled semiconductor rectifier and in which each ofthese series arrangements forms part of a branch connecting twoterminals of a first direct voltage source, each of the controlledsemiconductor rectifiers being provided with a control circuit ischaracterized in that a core of a magnetic material having asubstantially rectangular hysteresis loop and two stable remanencestates is added to each bulb, and that the control circuit of thecontrolled semiconductor rectifier arranged in series with a bulb isconnected to a first winding of the core added to said bulb, a secondwinding of said core forming part of one of the branches connecting thetwo terminals of the first direct voltage source together andaccommodating one of the other bulbs, a third winding of the core addedto a bulb arranged in series with corresponding windings of the coresadded to the other bulbs being connected to an auxiliary arrangement forgenerating a shift pulse.

An advantage of an arrangement according to the invention is that theinterconnection to a subsequent flash bulb can be realized with a smallnumber of elements namely magnetic cores. It is ensured beforehand thatonly one of these cores is located in a preferred position. Subsequentlythe said core is brought to its other stable remanence state by means ofa shift pulse. As a result a voltage is applied to the control circuitof a controlled semiconductor rectifier via the so-called second windingof this core. This semiconductor rectifier is rendered conductingthereby so that the flash bulb arranged in series therewith flashes. Thesaid shift pulse does not have any influence on the other cores of thearrangement because these cores were not located in their preferredposition. By flashing the said bulb a current will flow which causes thecore added tothe subsequent bulb to be changed over to its otherremanence state. The result of all this is that only one core is locatedin its preferred position again, namely the core which is added to thesubsequent bulb in the rowv of bulbs. .When a subsequent shift pulse isapplied to the third winding of the cores, the subsequent bulb willflash in a manner similar to that as described hereinbefore, etc.

It is to be noted that it is known from Swiss Pat. Specification No.382,224 to use cores having three windings in a circuit in which one ofthese windings receives a shift pulse and in which always a subsequentcore is brought to the preferred position. In this known circuit theduration of the current through a user is, however, dependent on theduration of conductance of a transistor arranged in series with saiduser. For use in combustion flash bulbs this is a drawback becauseeither the flash bulb does not sufficiently flash or extra auxiliarycircuits are required to maintain the transistor conducting for a longerperiod.

It is not necessary that a flash bulb in an arrangement according to theinvention is only in series with one of the controlled semiconductorrectifiers. It is alternatively possible for this bulb to be arranged inseries with, for example, two of the controlled semiconductorrectifiers.

The shift pulse may be generated, for example, in an auxiliary circuitwhich is provided with a controlled semiconductor rectifier renderedconducting for a short period and which is arranged in series with thesocalled third windings of the cores.

In a preferred embodiment according to the invention in which the shiftpulse auxiliary arrangement is also provided with a core of a magneticmaterial having a substantially rectangular hysteresis loop and twostable remanence states, the latter core has a first winding which isconnected through a switching element to a first auxiliary voltagesource, and the series arrangement of the third windings of the coresadded to the bulbs is connected to a second winding of the core of theshift pulse auxiliary arrangement, the branches comprising the bulbs andconnecting the two terminals of the first direct voltage source togetheralso accommodating a further winding of the core of the shift pulseauxiliary arrangement.

An advantage of this preferred embodiment is that the shift pulseauxiliary arrangement may be very simple. The core in this shift pulseauxiliary arrangement is brought to the other remanence state due to theswitching element being rendered conducting so that the shift pulse isgenerated. This pulse is then applied through the third windings of thecores added to the bulbsFinally the core of the shift pulse auxiliaryarrangement is reset to the original remanence state by the returncurrentof the bulbs. Then this core in the shift pulse auxiliaryarrangement is thus ready again for generating a subsequent shift pulse.

It is feasible that the return currents of the bulbs flow throughdifferent further windings of the core of the shift pulse auxiliaryarrangement.

In a further preferred embodiment of an arrangement according to theinvention in which the branches comparing the bulbs and connecting thetwo terminals of the first direct voltage source together have a commonconductor part, the further winding of the core of the shift pulseauxiliary arrangement is present in this common conductor part.

An advantage of this preferred embodiment is that the number of windingson the common core, that is to say, the core of the shift pulseauxiliary arrangement may be very small.

It is feasible, that the sequence viewed from the positive terminal tothe negative terminal of the first direct voltage source is completelyarbitrary for, the bulbs the controlled semiconductor rectifier and thesecond winding of a core.

In a preferred embodiment according to the invention in which in eachbranch comprising a bulb and connecting the two terminals of the firstdirect voltage source together the bulb is located closer to thepositive terminal of the first direct voltage source than the controlledsemiconductor rectifier forming part of said branch and the secondwinding of a core added to one of the other bulbs, the end of each bulbremote from the positive terminal is connected to its own secondauxiliary voltage source of limited capacity.

An advantage of this preferred embodiment is that if a bulb is defectiveor if it were removed from its holder, a current still flows through therelevant second winding of the core when the controlled semiconductorrectifier becomes conducting, which current brings this core to itsother remanence state. This current is then withdrawn from this secondauxiliary voltage source of limited capacity. When the second auxiliaryvoltage source is discharged, the controlled semiconductor rectifier, ifchosen to be a thyristor, will become nonconducting again.

In a further improvement of the latter preferred embodiment the secondauxiliary voltage sources of limited capacity each consist of acapacitor which is connected in series with a resistor to a seconddirect voltage source. This capacitor is thus always charged throughthis resistor. The RC-time is chosen to be such that during discharge ofthe capacitor substantially no current flows through the resistor.

It is feasible that in the factory where an arrangement according to theinvention is made one of the cores is already set to its preferredposition and the other cores are set to the non-preferred position.

In a further preferred embodiment according to the invention in whichthe switching element in series with the first winding of the shiftpulse auxiliary arrangement is a thyristor, the control electrode ofthis thyristor is connected through a flash contact of a photocamera tothe positive terminal of a second direct voltage source.

An advantage of this embodiment is that the user of the arrangement canbring the cores to the nonpreferred position himself without flashing.In fact, it is feasible that sometimes more than one of the cores hascome to its preferred position while this is not desirable. The usedswitch shunting the flash contact may then serve for a renewed setting,also sometimes referred to as reset.

When such a reset has taken place it is also to be ensured that it ispossible to subsequently place one of the cores in its preferredposition again. This may be effected by providing, for example, one ormore of the cores with extra windings and by subsequently connectingthem to a voltage source.

In a further embodiments of the latter preferred arrangement accordingto the invention in which a first switch connected in parallel with theflash contact is present between the control electrode of the thyristorand the positive terminal of the second direct voltage source, thisfirst switch is mechanically coupled to an auxiliary switch in a partwhich is common for (n l) of the branches, where n is the number ofbulbs, an in the open state of the first switch the auxiliary switch isclosed, and in the closed state of the first switch the auxiliary switchis open.

An advantage of this preferred embodiment is that during the reset acurrent which is not too large flows through a winding of the core ofthe shift pulse auxiliary arrangement. A too large current is thenprevented by the so-called auxiliary switch.

In a further preferred embodiment according to the invention a thirdauxiliary voltage source is connected through a second switch to thesecond winding of a core added to one of the bulbs, which second windingis present in that branch which connects the terminals of the firstdirect voltage source and which is free from the auxiliary switch.

An advantage of this embodiment is that by closing this switch therelevant core can be brought to its preferred position in a simplemanner after resetting. The preferred position is then understood tomean a remanence state of the core which is reversed when a shift pulseis applied to the core.

The invention will be described in greater detail with reference to adrawing. In this drawing:

FIG. 1 shows an electrical circuit diagram of a first arrangementaccording to the invention;

FIG. 2 shows a second electrical circuit arrangement according to theinvention.

In FIG. 1, 1 denotes a low-voltage combustion flash bulb. 2, 3 and 4 aresimilar combustion flash bulbs. A core provided with three windings isadded to each bulb. For bulb 1 this is core K1, for bulb 2 it is K2, forbulb 3 it is K3 and for bulb 4 it is K4. 5 is an input terminal of thearrangement which is intended to be connected to the positive terminalof a direct voltage source. The terminals 6 and 6a to 6d are allconnected to the negative terminals of said direct voltage source. Theterminal 5 is connected to a resistor 7. The other end of this resistor7 is connected to a capacitor 8. The other end of this capacitor 8 leadsto the negative terminal 6b of the direct voltage source. The lamps l to4 are arranged in parallel and are connected to the junction of theresistor 7 and the capacitor 8. The other end of the bulb l is connectedto a controlled semiconductor rectifier Tl, a thyristor. The cathode ofthis thyristor T1 is connected to a winding W22 of the annular core K2of a magnetic material having a rectangular hysteresis loop and tworemanence states. The other end of winding W22 is connected to a commonreturn lead 9. This return lead is connected through an auxiliary switch18a and a winding N2 of a further core G to the negative terminal 6d ofthe direct voltage source. The core G constitutes the most importantpart of a shift pulse auxiliary arrangement.

Furthermore the thyristor T1 is provided with a control circuit. Thiscontrol circuit is connected to a first winding Wll of the core Kl. Oneend of the winding Wll is connected through a diode 11 to a capacitor12. The junction between the diode 11 and the capacitor 12 is connectedto the control electrode of the thyristor T1. The other end of thecapacitor 12 is connected to the cathode of the thyristor T1.

The bulb 2 is arranged in series with a thyristor T2. The bulb 3 isarranged in series with a thyristor T3, and the bulb 4 is arranged inseries with a thyristor T4. The thyristors T2, T3 and T4 are providedwith a control circuit similarly as the thyristor T1. The controlcircuit of the thyristor T2 is connected to a winding W21 of the coreK2. The core K2 is furthermore provided with a third winding W23.Windings similar to those of W23 are also provided in the form ofwinding W13 on the core K1, as winding W33 on the core K3 and as windingW43 on the core K4. The'windings W43, W33, W23 and W13 are arranged inseries and are connected through a diode to a winding N3 of the coreG inthe shift pulse auxiliary arrangement. The other windings of the core K3are denoted by W32 and W31. The other windings of the core K4 aredenoted by W42 and W41. The other winding of core K1 is denoted by W12.The core G has a winding N1 one end of which is connected to a junctionbetween a resistor 14 and a capacitor 15 which constitute a connectionbetween the positive terminal 5 and the negative terminal 6 of thedirect voltage source. The other end of the winding N1 is connectedthrough a thyristor 16 to the terminal 60. The control electrode of thethyristor 16 is connected to a contact 17 of the camera flash contact aswell as to a switch 18. This switch 18 is mechanically coupled to theauxiliary switch 18a. The other end of the switch 18 is connected boththrough a resistor 20 to the positive terminal 5 and to the other end 19of the camera flash contact. 21 denotes a resistor which in series witha capacitor 22 is connected between the positive terminal 5 and thenegative terminal 6a of the direct voltage source. The junction betweenthe resistor 21 and the capacitor 22 is connected through a switch 23 toa point between the thyristor T4 and the'winding W12 of the core K1. I

Finally'a series arrangement of a resistorand a capacitor is added toeach bulb. These are the resistor R1 and the capacitor C1 for bulb 1.The junction between this resistor R1 and the capacitor C1 is connectedto a junction between the bulb l and the thyristor T1. Similarly, aseries arrangement of a resistor R2 and a capacitor C2 is added to bulb2. Further there are resistor R3 and capacitor C3 for bulb 3 andresistor R4 and capacitor C4 for the last bulb (4).

The circuit described operates as follows. Firstly the switch 18 isbrought to its closed state and consequently the auxiliary switch 18a isbrought to its open state. As a result thyristor 16 will be renderedconducting. This means that the previously charged capacitor 15 isdischarged across the winding N1 of the core G and across the saidthyristor 16. Consequently, the remanence state of the core G ischanged. This results in a voltage induction in the winding N3 of thecore G, which is passed over the shift line via the diode 10 across thewinding W13, W23, W33 and W43 of the cores. All these cores will then bebrought to the socalled non-preferred position (reset). A possiblereturn current through winding N2 and originating from the resistor 20so that this thyristor becomes conducting. As a result the capacitor 15will again be discharged through the winding N1 and the remanence stateof 1 core G will be reversed so that a pulse is again given through theshift line. This shift line will not bring about anything for the coresK2, K3 and K4, but the remanence state of core K1 will now be reversedto the nonpreferred position. As a result a pulse will be generated inthe winding W11, which pulse renders the thyristor T1 conducting.Consequently the bulb 1 flashes. The current flowing in the circuit 8,1, T1, W22, N2, 6d will firstly bring the core K2 to its preferredposition and furthermore reset the core G to its original remanencestate again. When subsequently the camera flash contact is operated fora second time the magnetic state of the core K2 will be reversed by theshift pulse so that the thyristor T2 is rendered conducting. The othercores are not influenced in this case because all of them, also the coreK1, are in their non-preferred position, etc. If the thyristor T4 isrendered conducting a current flows through the winding W12 of the coreK1 so that this first core is set to its preferred position again. Iffor some reason or other a bulb might be defective or removed from itsholder, the relevant capacicapacitor C4, across winding W12, will bringthe core G to its original remanence state.

Subsequently switch 18 is opened and switch 180 is closed. The switch 23is then closed so that the capacitor 22 is discharged across the windingW12 and the winding N2. As a result the core K1 is brought to thepreferred position and the remanence state of core G is reversed. Thearrangement is then ready for flashing.

tor added thereto, for example, C1, C2, C3 or C4 will be dischargedthrough the relevant thyristor, that is to say, T1, T2, T3 or T4 andthen still set the next core to its preferred position. v

The arrangement for resetting and writing in with the resistor 21,capacitor 22 and switch 23 may be omitted if the preferred position ofonly one of the cores is set in the factory where the arrangement ismade and if the cores are sufficiently shielded from magnetic fields. Inthat case the thyristor 16 may also be omitted and the camera flashcontact may be provided between the winding N1 and the negative terminal6d of the direct voltage source.

In the circuit described the number of control elements is only small bythe choice of the annular cores, and generating of the shift pulse isvery simple. The return current for the bulbs is used to reset thecommon core to its original remanence state.

The arrangement of FIG. 1 may be provided, for example, at least partlyon a printed wiring board (integrated circuit).

The arrangement of FIG. 1 may be accommodated, for example, for a largeror smaller part in a photocamera. It is also feasible that thisarrangement is formed as an adapter which constitutes the connection between a camera and an expandable flash bulb unit. This unit accommodatesthe bulbs 1 to 4. The invention relates of course also to arrangementsin which the number of bulbs is larger or smaller than four.

In a practical embodiment the cores K1 K4 were ferrite cores. Theresistor 7 had a value of approximately 2.2 k. ohm and the capacitor 8had a value of approximately 200 #F. The resistors R1 R4 each had avalue of approximately 47 k.ohm and the capacitors Cl C4 had a value ofapproximately 2.2 F. The capacitor 12 had a capacitance of approximately47 kpF. The resistors 14 and 21 each had a value of approximately 47k.ohms and the capacitors 15 and 22 had a capacitance of approximately 1MP and 6.8 11F, respectively.

FIG. 2 shows a slightly different circuit using five bulbs denoted by101 to 105. These again are low voltage combustion flash bulbs. 106denotes the positive terminal of a direct voltage battery "and 107denotes the negative terminal of this battery. Bulb 101 is in serieswith a thyristor T101 and with awinding D12 of a core Bl. Bulb 102 is inseries with a winding D22 of a core B2 and a thyristor T102. Bulb 103 isin series with the thyristor T101 and with the winding D32 of a core B3.In addition this bulb 103 is in series with the thyristor T102. The bulb104 is in series with the thyristor T102. The bulb l04 is in series witha thyristor T104 and with a winding D42 of a core B4. The bulb 105 isalso in series with the thyristor T104 and in addition with a windingD52 of a core B5. The windings D13, D23, D33, D43 and D53 of the fivecores are connected in series and are connected to a shift pulseauxiliary arrangement 108. As in the case of FIG. 1 the return currentof the bulbs flows through a core'(15) of the shift pulse auxiliaryarrangement. The sequence in which the bulbs are flashed is 101, 102,103, 104, 105. To this end the thyristor T101 is rendered conducting andsubsequently the thyristor T102 is rendered conducting. Subsequentlyboth the thyristor T101 and the thyristor T102 are rendered conductingso that the bulb 103 flashes. Finally the thyristor T104 is renderedconducting. Subsequently both the thyristor T104 and the thyristor T102are rendered conducting for flashing the last bulb 105.

All this is realized by causing the core B1 to reverse when the bulb 101is flashed, and by causing the core B2 to reverse when the bulb 102 isflashed while for the next shift pulse the core B2 applies a triggerpulse both to thyristor T101 and to thyristor T102 so that the thirdbulb, namely bulb 103 is subsequently flashed. Similarly, when applyinga shift pulse to the core B4 set to its preferred position a controlsignal is passed both to thyristor Tl04 and to thyristor T102 causingthe bulb 105 to be flashed. I

An advantage of the arrangement of FIG. 2 is that only three thyristorsare required for flashing five bulbs.

What is claimed is:

1. An arrangement provided with at least two combustion flash bulbs andwith controlled semiconductor rectificrs for successively igniting saidbulbs, each bulb being arranged in series with such a controlledsemiconductor rectifier and in which each of said series arrangementsforms part of a branch connecting two terminals of a first directvoltage source, each of the controlled semiconductor rectifiers beingprovided with a control circuit, characterized in that a core of amagnetic material having a substantially rectangular hysteresis loop andtwo stable remanence states is added to each bulb, and that the controlcircuit of the controlled semiconductor rectifier arranged in serieswith a bulb is connected to a first winding of the core added to saidbulb, a second winding of said core forming part of one of the branchesconnecting the two terminals of the first direct voltage source togetherand accommodating one of the other bulbs, a third winding of the coreadded to a bulb arranged in series with corresponding windings of thecores added to the other bulbs being connected to an auxiliaryarrangement for generating a shift pulse.

2. An arrangement as claimed in claim 1, in which the shift pulseauxiliary arrangement is also provided with a core of a magneticmaterial having a substantially rectangular hysteresis loop and twostable remanence states, characterized'in that the latter core has afirst winding which is connected through a switching element to a firstauxiliary voltage source, the series arrangement of the third windingsof the cores added to the bulbs being connected to a second winding ofthe core of the shift pulse auxiliary arrangement, the branchescomprising the bulbs and connecting the two terminals of the firstdirect voltage source together also accommodating a further winding ofthe core of the shift pulse auxiliary arrangement.

3. An arrangement as claimed in claim 2 in which the branches comprisingthe bulbs and connecting the two terminals of the first direct voltagesource together have a common conductor part, characterized in that thefurther winding of the core of the shift pulse auxiliary arrangement ispresent in said common conductor part.

4. An arrangement as claimed in claim 1, in which in each branchcomprising a bulb and connecting the two terminals of the first directvoltage source together the bulb is located closer to the positiveterminal of the first direct voltage source than the controlledsemiconductor rectifier forming part of said branch and the secondwinding of a core added to one of the other bulbs, characterized in thatthe end of each bulb remote from the positive terminal is connected toits own second auxiliary voltage source having a limited capacity.

5. An arrangement as claimed in claim 4, characterized in that thesecond auxiliary voltage sources of limited capacity each consist of acapacitor which is connected in series with a resistor to a seconddirect voltage source.

6. An arrangement as claimed in claim 2 in which the switching elementin series with the first winding of the shift pulse auxiliaryarrangement is a thyristor, characterized in that the control electrodeof said thyristor is connected through a flash contact of a photocamcrato the positive terminal of a second direct voltage source.

7. An arrangement as claimed in claim 6, characterized in that a firstswitch connected in parallel with the flash contact is present betweenthe control electrode of the thyristor and the positive terminal of thesecond direct voltage source, said first switch being mechanicallycoupled to an auxiliary switch in a part which is common for (n l) ofthe branches, where n is the number of bulbs, and in which in the openstate of the first switch the auxiliary switch is closed, and in theclosed state of the first switch the auxiliary switch is open.

8. An arrangement as claimed in claim 7, characterized in that a thirdauxiliary voltage source is connected through a second switch to thesecond winding of a core added to one of the bulbs, said second windingbeing present in that branch which connects the terminals of the firstdirect voltage source and which is free from the auxiliary switch.

1. An arrangement provided with at least two combustion flash bulbs andwith controlled semiconductor rectifiers for successively igniting saidbulbs, each bulb being arranged in series with such a controlledsemiconductor rectifier and in which each of said series arrangementsforms part of a branch connecting two terminals of a first directvoltage source, each of the controlled semiconductor rectifiers beingprovided with a control circuit, characterized in that a core of amagnetic material having a substantially rectangular hysteresis loop andtwo stable remanence states is added to each bulb, and that the controlcircuit of the controlled semiconductor rectifier arranged in serieswith a bulb is connected to a first winding of the core added to saidbulb, a second winding of said core forming part of one of the branchesconnecting the two terminals of the first direct voltage source togetherand accommodating one of the other bulbs, a third winding of the coreadded to a bulb arranged in series with corresponding windings of thecores added to the other bulbs being connected to an auxiliaryarrangement for generating a shift pulse.
 2. An arrangement as claimedin claim 1, in which the shift pulse auxiliary arrangement is alsoprovided with a core of a magnetic material having a substantiallyrectangular hysteresis loop and two stable remanence states,characterized in that the latter core has a first winding which isconnected through a switching element to a first auxiliary voltagesource, the series arrangement of the third windings of the cores addedto the bulbs being connected to a second winding of the core of theshift pulse auxiliary arrangement, the branches comprising the bulbs andconnecting the two terminals of the first direct voltage source togetheralso accommodating a further winding of the core of the shift pulseauxiliary arrangement.
 3. An arrangement as claimed in claim 2 in whichthe branches comprising the bulbs and connecting the two terminals ofthe first direct voltage source together have a common conductor part,characterized in that the further winding of the core of the shift pulseauxiliary arrangement is present in said common conductor part.
 4. Anarrangement as claimed in claim 1, in which in each branch comprising abulb and connecting the two terminals of the first direct voltage sourcetogether the bulb is located closer to the positive terminal of thefirst direct voltage source than the controlled semiconductor rectifierforming part of said branch and the second winding of a core added toone of the other bulbs, characterized in that the end of each bulbremote from the positive terminal is connected to its own secondauxiliary voltage source having a limited capacity.
 5. An arrangement asclaimed in claim 4, characterized in that the second auxiliary voltagesources of limited capacity each consist of a capacitor which isconnected in series with a resistor to a second direct voltage source.6. An arrangement as claimed in claim 2 in which the switching elementin series with the first winding of the shift pulse auxiliaryarrangement is a thyristor, characterized in that the control electrodeof said thyristor is connected through a flash contact of a photocamerato the positive terminal of a second direct voltage source.
 7. Anarrangement as claimed in claim 6, characterized in that a first switchconnected in parallel with the flash contact is present between thecontrol electrode of the thyristor and the positive terminal of thesecond direct voltage source, said first switch being mechanicallycoupled to an auxiliary switch in a part which is common for (n -1) ofthe branches, where n is the number of bulbs, and in which in the openstate of the first switch the auxiliary switch is closed, and in theclosed state of the first switch the auxiliary switch is open.
 8. AnaRrangement as claimed in claim 7, characterized in that a thirdauxiliary voltage source is connected through a second switch to thesecond winding of a core added to one of the bulbs, said second windingbeing present in that branch which connects the terminals of the firstdirect voltage source and which is free from the auxiliary switch.